1. Field of the Invention
The present invention relates to an apparatus for driving a display panel, and more particularly, to an apparatus for driving a plasma display panel (PDP).
2. Discussion of the Background
In a plasma display panel (PDP), which is a type of flat panel display, a discharge gas is filled between two substrates, on which a plurality of electrodes is formed on each substrate. A discharge voltage is applied between two of the electrodes, and phosphors arranged in a pattern are excited by ultraviolet light generated by the discharge voltage, thereby displaying a desired image.
By applying driving signals to the electrodes, a discharge is generated in discharge cells formed by the electrodes. First, a driving signal is applied to electrodes corresponding to selected discharge cells to be turned on. Then, a driving signal, called a sustain pulse, is applied to the selected discharge cells, so that a sustain discharge is generated in the selected discharge cells. The sustain pulse alternates between two voltages, a first voltage and a second voltage, which may be a ground voltage, and the brightness of the light emitted from each discharge cell is determined according to the number of applied cycles of the sustain pulse.
Since the sustain pulse applied to the electrodes of a PDP alternates between the predetermined voltage and the ground voltage as described above, a peak current occurs in the circuitry of the PDP. The peak current occurs when the sustain discharge is generated in the discharge cells of the PDP, and the peak current generates an electromagnetic wave within the PDP.
Generally, the electromagnetic wave intensity increases as the duration of the sustain pulse increases, as the rate of voltage change with respect to time increases, and as the rate of current change with respect to time increases. Furthermore, when a sustain pulse is applied to selected discharge cells while the PDP is generating a sustain discharge, large changes occur in current and voltage with respect to time, and the intensity of the electromagnetic wave can increase. An electromagnetic wave generated in the circuitry of the PDP has a detrimental effect on the PDP driving apparatus and on the PDP.
For these reasons, efforts have been made to minimize the generation of the electromagnetic wave. For example, a method has been developed which varies the frequency of the sustain pulse. However, the method may result in an unstable sustain discharge, which can decrease brightness of emitted light. Another method connects a capacitor between the terminals of switches that apply voltages to the PDP, thereby removing high-frequency noise generated when the switches perform the switching operations and avoiding electromagnetic interference (EMI). However, with this method, output waveforms can be distorted. Additionally, the heat generation by the switches can increase if the total capacitance of the added capacitors is large. Finally, since capacitors must be connected to the switches, this method can result in high manufacturing cost.